This invention relates to a data processing system having a memory unit with auxiliary memory bits, and also to the protection and management of data used therein.
In the conventional data processing system, unique addresses are assigned, in numeric value, to individual data words. That is, an aggregate of data words is, in other words, an aggregate of addresses, constituting an address space. Moreover, the conventional data processing system circumvents the capacity limitations of the virtual memory by use of the real memory method, and serves as a system that can be used by a plurality of users without interference with one another through the provision of the data protection device to restrict the use of the memory unit by authorizing some program and user to use a data word.
In the virtual memory method, the virtual memory space and the real memory space are managed in units of continuous data words generally referred to as a page or a segment. The page and the segment are also used as the management units in the data protection device, and data protection information and authority to use are set for each page or segment.